[waiwai933]

S3 is great for being able to stick files somewhere and not have to think about any of the surrounding infrastructure on an ongoing basis [1]. You don't have to worry about keeping a RAID server, swapping out disks when one fails, etc.

For static hosting, it's fine, but as you say, it's not necessarily the cheapest, though you can bring the cost down by sticking a CDN (Cloudflare/CloudFront) in front of it. There are other use cases where it really shines though.

[1]: I say ongoing basis because you will need to figure out your security controls, etc. at the beginning so it's not totally no-thought.